3.33-Inch (Dj) Windows 



The 3.33-inch (Dj) windows were tested in groups of five and had t/Dj ratios 

 ranging from 0.036 to 0.600. For each group the critical pressure was plotted 

 against the t/Dj ratio (Figure B-20) and the pressure was plotted against deflection. 



Windows with t/D| ratios of less than 0.1 exhibited both the conical and 

 flexural failure modes, whereas windows with t/Dj ratios between 0.1 and 0.4 failed 

 only in the conical fracture mode previously described. Concentric cracking was 

 observed toward the upper t/Dj limit. These cracks propagated from the low-pressure 

 face. 



Shear failures were characteristic of windows whose t/D; ratios were greater 

 than about 0.4 (Figure B-16). Combined with the shear failure pattern were the 

 various combinations of radial and circumferential cracks discontinuous throughout 

 the window. Details of flanges used in testing the 3.33-inch (D-) windows are 

 shown in Figure B-21 and an in-place schematic is shown in Figure B-22. 



4.00-Inch (D|) Windows 



The t/D| ratios of the 4.00-inch (D|) specimens ranged from 0.058 to 0.498. 

 Four groups consisting of five windows each were used In the comparative study. 

 Critical pressure was plotted against the t/Dj ratio (Figure B-23) and pressure was 

 plotted against deflection. 



Results of limited testing of 4.00-inch (D|) windows were consistently 

 comparable with those for the 1.50-Inch, and 3.33-Inch (D;) specimens. Flexural 

 and conical surface failures were witnessed for t/D; ratios less than 0.1 and conical 

 failures were observed for t/Dj ratios between 0.1 and about 0.4. Shear failure was 

 dominant for t/Dj ratios greater than about 0.4. 



Details of flanges used In testing the 4.00-Inch (Dj) specimens are shown In 

 Figure B-24 and an in-place schematic is shown in Figure B-25. Extrusion, retained 

 as permanent set in the specimens (Figure B-26), Is summarized In Table B-1 for 

 specimens which were not pressurized to critical pressure. 



SUMMARY 



Failure mechanisms characteristic of the 1.50-inch (D;) windows were found 

 also to be characteristic of the 3.33-inch and 4.00-Inch (Dj) windows so long as 

 t/Dj ratios were similar. Critical pressures derived from testing of windows having 

 a different Dj in the DOL type III flange design were found to be comparable so long 

 as the Dq/Dj ratio was maintained at 1.5, temperatures were within the 65°F to 

 75°F range, and the radial clearance was kept to less than 0.010 Inch. 



41 



